Field of the Invention
The present invention relates to a link actuation device used in, for example, a parallel link mechanism or a robot articular mechanism which speedily and precisely execute a work such as, for example, a complicate processing or handling of articles in a three dimensional space and, more particularly, to a link actuation device, an operating device therefor, a method of controlling it and a control device therefor, all of which require a precise and extensive operating range of, for example, medical instruments and industrial equipments.
Description of Related Art
The parallel link mechanism adopted in an actuating device is disclosed in the patent documents 1 and 2 listed below.
Although the parallel link mechanism disclosed in the patent document 1 is relatively simple in structure, the actuating angle of each of links is small. Therefore, setting of the operating range of a traveling plate to a large value tends to result in increase of the link length and, also, the dimensions of the mechanism in its entirety is rendered to be so large, and as a result, the device tends to become bulky. Also, if the link length is increased, the rigidity of the mechanism in its entirety decreases. For this reason, there has been such a problem that the weight of tools that are mounted on the traveling plate, that is, the weight capacity of the traveling plate is limited to a small value. In view of those problems, it has been difficult to utilize the parallel link mechanism of the patent document 1 in, for example, a medical equipment of a compact structure that requires a precise and wide and extensive operating range.
In contrast thereto, the link actuation device disclosed in the patent document 2 is so designed and so configured that a distal end side link hub is connected with opposite to a proximal end side link hub through three or more sets of link mechanisms of a triple link chain type so that distal end side link hub can be altered in orientation. Accordingly, despite that the link actuation device is compact in structure, the operation is possible in the precise and extensive operating range. The distal end orientation, which is the orientation of the distal end side link hub relative to the proximal end side link hub, is determined by regulating the status of two or more sets of the link mechanisms out of the three or more link mechanisms. It is to be noted that the wording “to regulate the status of the link mechanism” referred to above and hereinafter or a similar wording to that effect is intended to speak, for example, the definition of the angle of rotation of one of the links of the link mechanism, which is connected with the distal end side link hub relative to the proximal end side link hub.